I had my 1991 YFM 250 top end rebuilt 2 years ago. It has had 200 miles (not ridden a lot) on the rebuild, but oil has begun to leak at the gasket between the crankcase and the head. I don't want to have to take it all apart again just for the gasket. It isn't a big leak, but does drip onto the pavement. Is there a "stop leak" product that will fix the problem without a tear-down? Other than that, it runs great.